Modern, multipurpose integrated circuits generally have a number of independently functioning units. These units are sometimes referred to as integrated peripheral devices or design blocks. For example, a design block may be a Universal Serial Bus (USB) host controller or a PCI Express® (PCIe) host controller. Integrated circuit manufacturing companies, to keep manufacturing costs down, might design an integrated circuit that has several design blocks and distinguish between different product models (i.e. different stock keeping units (SKUs)) by “fusing-out” one or more design blocks on a certain percentage of the manufactured units. When a design block is fused-out it is permanently disabled.
When there are a large number of design blocks in a product that are fused-out, a significant portion of the physical die space of the integrated circuit is not available for use (i.e. all the fused-out design blocks lie dormant). Many of these design blocks have internal static random access memory (SRAM) for use by the block. When a block is fused-out, the SRAM that was implemented specifically for the block is also disabled. Thus, otherwise usable SRAMs go unutilized in these scenarios.